Looks to me that the radiator size dependent change in radiation resistance V. frequency was not taken properly into account in this article. Also, the table on P.2 seems to indicate that no matter how many times we double the number of radiators in the series connection the output SPL will not change, but the consumed power will divide by 2 for every doubling (if the author's assumptions would hold true for going from 1 speaker to 2 speakers, it should hold true going from 2 to 4, and so on....as long as the speakers are "co-located"); that just doesn't seem likely.

It seems that it will not be necessary to make any special adjustment for multiple tapped horns - the proposed new multiple speakers response calculation method appears to correct the problem automatically :-).

Kind regards,

David

Good!

It will still likely be years before people don’t expect an increase in LF relative to upper response for multiple TH, but glad that that misconception may be dissuaded once the code change is implemented.

After no response to my questions from Wayne, still wondering how his measured increase of 1.5 dB at 30 Hz for a pair of his FLH compares to the “old” and “new” code ?

After no response to my questions from Wayne, still wondering how his measured increase of 1.5 dB at 30 Hz for a pair of his FLH compares to the “old” and “new” code ?

Not sure what you're asking for, Art. I posted measurements and Hornresp models, at least in the form that they are links in post 1288. I even wrote where to find what in each link, e.g. "Hornresp models in the following link", "measurements in the following link", and so on.

I always attributed the extra "boost" at low frequencies to the increased mouth size when going from one unit to two. The horn is physically large, but it isn't acoustically large. I would expect this behavior until the group was acoustically large, at around four units for the 12Pi. Same thing happens for LABhorns up to six units. Beyond that, I would expect SPL increases, but not "bass boost" from grouping. Once the FLH group is made acoustically large, it is most efficient all the way through the passband.

It seems that it will not be necessary to make any special adjustment for multiple tapped horns - the proposed new multiple speakers response calculation method appears to correct the problem automatically :-).

Thanks, Djim, for bringing the measurements and the models together, side-by-side. Easier to compare than pouring through all the threads linked from post 1288. Looks like there's pretty good agreement between the Hornresp model and the measurements. Beyond the 6dB increase, there's a smidge more from 45Hz to 65Hz and a smidge less from 65Hz to 100Hz. Maybe 1dB more down low and 1dB less up high, a total of ~2dB difference. That's pretty much what the Hornresp model shows, about 2dB less slope in the overall trend.

Your welcome Wayne, the differences are very small and in my view based on real life differences such as losses (driver) not represented by the model. However one thing I like to add, the model I used is based on your measurements to get an as close as possible model for 1 cab to see the difference between 1 and 2 cab measurement/modelling.